I made this invention in response to talking to users of outdoor video surveillance systems. The comments I kept hearing were that it's good to have images but no one has the time to constantly watch video looking for suspects, no one can remember enough of what they see to spot patterns in the presence of subjects, and they need help identifying the individuals.
The key questions are:                1) How does one determine when particular individuals are present, or if anyone is present ?        2) How does one determine if anyone was present previously, and if so, who ?        3) How can one put a name to a face ?        
The de-facto solution is video surveillance, but monitoring video from cameras, especially outdoor ones, to spot suspects is a daunting task. Humans lack the time to continuously watch surveillance video. They lack the memory to remember every person and vehicle and when they came and went during recent days or weeks, and spot patterns in this mountain of information. Distance, darkness, glare and vehicles conceal identities. Motion sensors that call your attention to video are useless with a busy street. Face recognition doesn't work at a distance or when you can't see a person's face well. Video analytics don't help when activity looks normal, and they don't determine identities. Tracking mobile phone numbers only works if you know which numbers to look for. Fighting terrorists and a multitude of crimes suffers.
I'm trying to answer simple questions:                1) has a particular person ever been present at a particular location during a particular period of time ?        2) when were they present ?        3) who was with them ?        4) how far was the person from the observation point ?        5) is that person there now ?        6) how can one be alerted when that person, or anyone, arrives ?        7) what do they and their vehicle, if any, look like ?        8) how can one associate a physical presence with a particular mobile device ?        9) how can one verify that the same person is carrying a particular mobile device ?        10) how can one electronically obtain enough information about a person whose identity is unknown to have probable cause and get a court order to compel the provider of a particular smartphone to identify its owner and provide other personal information about the mobile device ?        
Systems that monitor WiFi probes sent by mobile devices to find nearby WiFi hotspots are well known. Non-Patent Citations 1 through 5 give some articles on the subject. These systems are intended for retail applications to estimate foot traffic, determine when and where shoppers congregate and for how long, and determine the location of a cooperating subject and send immediately relevant advertising literature to that shopper. By a cooperating subject, I mean one who purposely makes the WiFi MAC address of his/her mobile device known to those who want it. While it is common to have surveillance cameras on streets and in stores, they and their recording devices are incidental to and not integrated with the WiFi monitoring systems.
In contrast, this invention is intended for outdoor law enforcement and public safety applications where persons do not want their locations and identities known. Since mobile devices can be shared and WiFi probes from mobile devices identify only the mobile device, not the bearer, this invention helps attach physical identity to the bearer of a mobile device via live and recorded video of the current and past presences of mobile devices. Since WiFi probes are sent by smartphones relatively infrequently, typically once every minute or two, and can be received outdoors from many mobile devices within one hundred yards of a receiver, one cannot easily determine which individual is associated with which mobile device. This ambiguity can be reduced by analyzing which mobile devices are present over time, and by reviewing recorded surveillance video from those multiple times to determine the recurring presence of certain individuals. Thus the ability to easily view multiple segments of recorded video from cameras in the area being watched is essential. And, the ability to enter the smartphone signatures, known as WiFi MAC addresses, of mobile devices of interest into a list that triggers the immediate sending of an alert that a particular mobile device is present, and enables viewing live and recorded video that is relevant to that particular WiFi MAC address, is essential. Law enforcement can use images of an individual committing a crime, combined with evidence that a particular mobile device is associated with that individual, to get a court to issue an order compelling the manufacturer of the mobile device to disclose the name of the owner of the mobile device, as well as information about the use of the mobile device.
While one could read the time a WiFi probe was received, manually select a video surveillance system that has one or more cameras viewing the area where WiFi probes are received, and manually enter the time into the video surveillance system to access recorded video, the process is tedious. It is not conducive to reviewing many video segments in an attempt to associate mobile devices with individuals or verifying whether or not the same person is carrying a particular mobile device.
In addition, the geographical environment of WiFi monitoring systems used for retail applications is shopping districts. In contrast, my focus is in any area where crime may be a problem. This includes residential neighborhoods where there is persistent WiFi traffic from AC-powered laptop computers and entertainment devices that access the Internet via a WiFi network. These devices, being AC-powered, often send WiFi probes every few seconds, not once every minute or two, as is common with battery-powered devices. Frequent probes are not useful and, since significant processing of probes may be required to implement filters to detect the MAC addresses of subjects' mobile devices, useless probes must be discarded early in the processing of probes so they do not overload the device receiving and processing the probes.